Cadmium plating



Patented lDec. 8 1925. V

UNITED STATES CLAYTON H. HOFF, OF CLEVELAND, OI IIO. ASSIGNOB TO THEGRASSEILI CHEMICAL I 1,564,414 PATENT OFFICE.

OOMZPANY, OF CLEVELAND, OHIO, A CORPORATION. 01 OHIO.

cnmmm rmrnve.

No Drawing.

To all whom it may concern:

Be it known that I, CLAYTON M. Horr, a

citizen of the United-States, residing at Cleveland, in the county ofCuyahoga and i 5 State of Ohio, have invented certain new and usefulImprovements in Cadmium Plating, of which the following is aspecification.

Thisinvention relates to the electroplat- 1 ing of cadmium and moreparticularly to a composition for that vpurpose.

In my application Serial No. 686,898,- filed Jan. 17 1924. I havedisclosed a process of electroplating cadmium involving the use of analkaline bath containing chemical combinations of cyanide, ammonium andcad mium, with or without addition agents such as gulac which may beprepared for instance by dissolving cadmium oxid or hydroxid or a saltsuch as cadmium sulfate in. aqua- 20 ammonia and adding thereto asoluble cyanide such as sodium cyanide.

Such .a bath is characterized by the fact that .from it pure, smooth anduniform de posits of cadmium may be producedrapidly and quantitativelyif des1red,j even when the bath contains other metals such as zinc.

, It is desirable for the chemicals manufac-'v turer to be able tosupplythe electroplater with the materials required ready for use,

but since itis not feasible to ship and-store the finished electrolating bath, it is one tomary when possib e to supply the electroplate'rwith a mixture of chemicals ready to be dissolved in water to producethe bath. It isIt-herefore', an object of my present invention'toprovide a dry mixture of chemi 'cals suitable ior storage and shipmentwhich when dissolved in .water, with or without other materials as willappear hereinafter,

4 will give a cadmium lating bath having in gene'rai the characteristicsof the bath disclosed'in my ap lication above referred to. In thecourseto my investigations in this connection for the pur ose of develo'ing' quch a dry mixture in chemicals I ave ound that baths having-thedesired characteristics may be prepared "in a variety of ways.

As stated above the bath of my earl er 9 application comprises as;essential ingredients or-components cadmium, ammonium. c anide and analkaline agent. Each of t ese components. may be suppliediin variousforms. For instancethe cadmium vcom- I l6 ponent may be supplied in theformy of the kali metals. T

my invention.

Application filed Qotobera, 1924. Serial mynama foxid, h droxid, orcyanide, or in the form of a sa t such as the sulfate. The cyanide comonent may besup lied in chemical com ination with the ca ium as cadmiumcyanide or as ammonium cyanide, or as other metal cyanides, preferablythose of the ale ammonium component ma besupplied in the form ofammonium hy roxide or as a salt such as ammonium cyanide or sulfate. Theammonium component apparently serves as the agent which prevents ortends to prevent the deposition of other metals, particularly zinc,along with the cadmium and may be replaced by other materials 'such assodium sulfate and other alkali metal salts. The alkaline reaction of.the bath may be produced by.

the use of ammonia or an alkali metal hydroxid. The bath referably ismade to contai'nalso a colloi agent, which tends to such as starch,gulac, dextrine, etc.

The following examples ofbath compositions illustrate my inyention;

Example 3 oz., cadmium hydroxide, 6 to 7 oz., sodium cyanide: to 1 oz.,caustic soda: to oz., sodium carbonate, and 1 oz., aqua ammonia" 26 B.-to each gallon of water; p

Ewample 2.

ing cadmium, cyanide. ammonium or another agent whihtends to prevent thecodeposition of. other metals such as zinc with 'or'witho'ut an additionag'enti'such as gulac may be produced in a-great variety of Ways, thatis'bv the use of a great-variet of chemicals; The relative proportionsofthe ingredients and the concentration of thegbath may of coursebe variedwithout departing from Of the great variety of combinations chemicalsindicated .a bo ve' only a vconi paratively few are well adapted from-animprove the quality ofthe cadmium plate,

.or since the shipment of caustic soda and cyanide is somewhatobjectionable, the electroplater may be supplied withv a mixture ofcadmium hydroxide, ammoniumsulfate and gulac with directions as to thequantity thereof to be dissolved in a given quantity of water along withcaustic soda and sodi-um cyanide separately supplied. Or theelectroplater maybe supplied with a dry mixture of cadmium hydroxide,sodium hydroxide,

I sodium cyanide and gulac, to which ammonia or an ammonium salt is tobe added in the preparation of the bath. These few examples as given aresuflicient for the purposes of illustration, it being understood thatthe invention is not limited to the particular combinations of chemicalsinstanced.

The electroplating from baths comprising the combinations of chemicalsdescribed may be carried out as disclosed in my prior application, forinstance at room temperature using a potential of 4 to 6 volts and acurrent density of l ampere per 100 square centimeters betweenelectrodes spaced about 15 centimeters apart, and preferably usingcadmium anodes with an anode surface area equal'to two or three timesthe cathode sur- .face area. Known expedients such as agitation orclrculatlon or heating or cooling of the bath, rotation of theelectrodes, etc., may be. employed.

I claim: a

1. A composition adapted for use in the electrodeposition of cadmiumcomprising a cadmium compound, a material which tends to prevent theco-plating of zinc with cadmium, an alkaline agent, a cyanide, and amaterial'which tends to improve the quality of cadmium platings.

.2. A composition adapted for use in the electrodeposition of cadmiumcomprising a cadmium compound, a material which tends to prevent theco-plating of zinc with cadmium,an alkaline agent and a cyanide.

pound, a caustic alkali, and an alkali metal cyanide.

5. A composition adapted for use in the electrodeposition of cadmiumcomprising cadmium hydroxide, an ammonium compound, an alkaline agentand a cyanide.

6. A composition adapted for use in the electrodeposition of cadmiumcomprising cadmium hydroxide, ammonium sulfate, an alkali metalhydroxide and an alkali metal cyanide. y

7. A composition of matter adapted for use for the preparation of acadmium plating bath consisting of a dry mixture com prising a cadmiumcompound and a material which tends to preventthe co-plating of zinc.

8. A composition of matter adapted for use for the preparation of acadmium plating bath consisting of a dry mixture comprising a cadmiumcompound and an ammonium salt. I i

9. A composition of matter adapted for use for the preparation of acadmium plating bath consisting of a dry mixture comprising cadmiumhydroxide and ammonium sulfate.

10. A composition of matter adapted for .nse for the preparation-of acadmium plating bath consisting of a dry mixture comprising a cadmmmcompound, a material which tends to prevent the co-plating of zinc,

and a material which tends to improve the quality of cadmium platings.

11. A composition of matter adapted for use for the preparation of acadmium plating bath consisting of a dry mixture comprising a cadmiumcompound, an ammoni-

